The mechanism of laser generation is spontaneous emission and stimulated emission. Spontaneous emission is that excited atoms spontaneously jump from high energy level to low energy level without any external force, and emit a photon at the same time. The first condition to generate laser is to realize the inversion of particle number. The medium that can realize the inversion of particle number is called active medium. In order to cause the inverse distribution of particle number, it is necessary to have an appropriate energy level structure and necessary energy input system in the medium.
Introduction to laser:
Laser is another great invention after nuclear energy, computer and semiconductor since the 20th century. Known as the fastest knife, the most accurate ruler and the brightest light. The English name of radiation stimulated emission light amplification means stimulated radiation light amplification. The English full name of laser has fully expressed the main process of making laser. The principle of laser was discovered by Einstein, a famous American physicist, as early as 19 16.